Means for improving the power factor of alternating-current circuits.



PATENTED APR. 2 1907.

M. 0. TROY.

URRENT mommy APPLICATION FILED SEPT. 21, 1904.

x x x x x x A x X0 x x x x x x w m w J UNITED STATES,

PATENT. OFFICE.

V MATTHEW o. TROY, or SCHENECTADY, NEW Y R ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION on NEW YORK.

MEANS FORIMPROVING THE POWER F'A'cToR .OF-AIi TERNATiNG-CURRENT cmcuns.

' 'Specificationof Letters Patent.

Patented April 2, 1907;

Application filed geptembr 21, 1904. Serial No. 226,308

To all whom it may concern:

Be itkn'own that I, MATTH W O. TROY, a

- citizen of the United States, residing at Schenectady, county York, have invented certain. new and useful of Schenectady, State of New Improvements in Means forfImproving the Power Factor ofAlternating-Current Circuits, of whichthe following n is a specification.

My present invention comprises means. for improving the power factor of alternating-- currentcircuits supplying inductive loadssuch-for example, as constant-current transnect in shunt to the circuit inwhich the power formers, constant-current reactive coils, or the like. a

Incarrying my invention into practice various modified embodiments of my invention may be utilized. Ordinarily, however, I confa'ctor is low a condenser prpvided with means, arranged m'accordance i'wnth my invention, for rendering the action of said con-Q denser 'efiective. If a condenseralo'ne ,be

I placed across a'. low-power-factor circuit, it

will generally be found that instead of improving the power factor, 'asmight be expected, there is either very little improve- Inent or none at all. This is due to the fact thatthe condenser tends toaccentuate the harmonics in the electromotive-force wave insuch a manner as to interfere with if not entirely prevent for the lagging current of the'load. I have found that this objectionable action may be eliminated and the beneficial effect of the condenser obtained by including in the cir cuit of the condenser an inductance sufficient to damp out the objectional harmonics and increasing the capacity of the condenser by ance The preponderating magnitude of the 'condenser is then free to take from the source a leading current sufficient under some conditions of load to compensate entirely for the lagging current of t e load and at other conditions to improve greatly the,

power factor over that which would exist without the use of the condenser.

The novel features which characterize my invention Ihave pointed out with particularity in the appended claims. The invention itself, however, will be better understood by reference to the following description, taken in connection with'thev accom panying drawings, in which Figure 1 represents a system embodymg the expected compensation" 'fication thereof.

' In Fig. 1 a source of alternating current is conventionally indicated at'l and the'mains extending therefrom at 2 and 3. A movingcoil constant-current transformer of a welli one form of mv invention, and Fig.- 2 a modiwinding .5 of this transformer receives curthe mains 2 and 3. The secondary 8 is connected to the constant-currentconsumptioncircult 9, which includes lamps or other suitable translatln'gdevices.

-10. The primaryfi is in a fixed position rela tive to the core, while the secondary 8 is stood .manner by the weighted lever-arm 11.

rent taken from the mains 2 and 3 by the transformer 4, which lagging current, espe-. i cially at light loads, lowers the power factor of the'system materially, I connect in shunt with the primary leads 6 and 7 a condenserinductance combination, which in the particular form shown in- Fig. 1 consists of a'confrom the leads 6 and 7 a leading current of the amount necessary to'neutral ize as far as possible the lagging current taken by the transformer 4. Inasmuch as the load on a and inductance chosen is necessarily a comcuit in connection with which" my invention is used.

nitude that the volt-amperes taken by ita're about one-quarter those taken by the condenser.

Where the voltage of the circuit inconnection with which the condenser is to be used is not high, it is of considerable advantage to known type is illustrated at 4'. The primary Both of these coils are mounted on the three-legged core i In order to compensate for the lagging curdenser 12 in series with the inductance-coilpromise, and depends upon the primary cir' As between the condenser and inductance,'however, I generally find is preferable to choose the inductance of such magrent from the leads 6 and 7,connected across practically counterbalanced in a we'll-underdenserlarge enough so that its preponderating effect is of a magnitude sufficient to draw transformer is variable, the value of condenser IOO supply the condenser with current inductively derived from the circuit. The voltage impressed upon the condenser from the secondary of the transformer or compensator, as the case may be, may thus be raised to any desired amount, and the size of the condenser required thus reduced correspondingly. In

such a case I design the transformerso as to.

have in itself such an amount of inductance as to eliminate the'necessity for a separate inductance,such as 13 inFig, 1. Such an arrangement is shown in Fig, 2, in which the leads 14 and 15 corres 0nd to the leads 6 and- 7 in Fig.1. -These eads'are supposed to supply energy to a circuit takin low-powerfactor current. v The condenser or overcom ing this low-power factor, as indicated at 16, is connected, as shown, to the secondary windings '17 of a transformer of s ec'ial construction.

portioned so as to replace the effect which would be given by corresponding inductance directly in series with the condenser 16.

It is evident that various modifications. of my invention may be employed without de- These windings are ocated at' one end of the core 18 and the corresponding parting from the spirit thereof, for which reason 1 do not Wish to be limited to the exact details shown and described.

What I claim as new, and desire to secure by Letters Patent of the United States, is 1. The combination of an alternatingcur rent supply-circuit, a consumption-circuit including a device or de'vices taking lagging current from the supplycircuit,' and means for improving the power factor of said supply-circuit consisting of a condenser and an inductance in series with each other inacircuit independent of said consumption-circuit.

2. The combination of a source'of alternating current, a circuit taking lagging current therefrom, and an independent circuit taking lea'ding current from said source, the lastmentioned circuit including a condenser provided with means for eliminating the effect of minorharmonics.

3. The combination of a source of alternating current, a constant-current circuit suplied with'energy from said source, a circuit ed from said source independently of said constantrcurrent circuit and including a condenser .wlth means for eliminating the effect of harmonics on sald condenser.

In witness whereof I have hereunto set my- VVitnesses'.

BENJAMIN B. HULL, HELEN ORFORD. 

